Grinding machine



Dec. 14, 1937. F. E. JOHNSON GRINDING MACHINE Filed Oct. 12, 1936 '7 Sheets-Sheet l FRANKLIN E. JOHNSON Dec. 14, 1937. F. E. JOH-NSON 2,102,518

' GRINDING MACHINE Filed Oct. 12, 1936 '7 Sheets-Sheet 2 Snuentor FRANKLIN E. JOHNSON orneg -Dec. 14, 1937. JOHNSQN 2,102,518

GRINDING MACHINE Filed Oct. 12, 1936 '7 Sheets-Sheet 5 ZSnuentor FRANKLIN E. JOHNSON Gttor Dec. 14, 1937. E, JOHNSON 2,102,518

"GRINDING MACHINE- Filed Oct. 12, 1936 7 sheets-Sheet 5 mwllm mi'i x: mm

MEX

ZSnuentor FRANKLIN E. JoH/vsb/v C(ltomeg Dec. 14, 1937. JQHNSQN 2,102,518

GRINDING MACHINE Filed Oct. 12, 1936 7 Sheets-Sheet e ISrwentor FRANKLIN E. JOHNSON (Ittorn Dec. 14, 1937.

'7 Sheets-Sheet 7 M J N .T I, 3 53 0 2 j M m m s wa M W W H I w 2 I. Z 3 B5 4 2 2 a 550 a 2/1 4 3 H 3 H 2 0 m 2 a W l 1 J 5/ r I M 55 m d 2 G 55 n N. H N w Q an. Mg 1 1 x w u \rg U 1 K (5 1..., aw w N 2% 3 I 5 1 Mt M s r m\\ u I zu /w 20 2 j F 0 I ,3 4 02 .5 b 4 m 2 Y Z 22 2,: 4 L y a 2 M 7 W a 7 1 a 5 I a. 2% 0 -0 m9 3 2 5 7 2 a 0 7 l r /m m/ A H know 3 m 3 2 lll ,2 N 47/ r .611 0 a7, 2 1w H .w I a I 6 L a, 5 a m m I flu w M- Patented Dec. 14, 1937 PATENT OFFICE.

GRINDING Franklin E. .lohnson, Worcester, Mass., assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application October s, 1936, Serial No. 105,157

* 8 Claims. Y (].51-165) "The invention relates to grinding machines and with regard to its more specific features to a work calipering mechanism therefor.

One object of the invention is to provide a calipering mechanism which can readily be maintainedat a given adjustment and is highly accurate. One object of the invention is' to provide a sensitivecalipering mechanism. Another object of the invention is to provide a calipering mechanism adapted to give excellent results in actual practical operation. Another object of the invention is to provide a contact'calipering mechanism the contact of which shall not mar the surface of a work piece. Another object of the invention is to provide a contact calipering device having smooth contact surufaces. ject of the invention is to provide a combined caliper and steadyrest: Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicatedin the following claims.

In the accompanying drawings, in which is shown one of various possibleembodiments of the mechanical features of this invention,

Fig. 1 is a verticalsectional view of a grinding machine constructed in accordance with the invention,

Fig. 2 is an enlarged fragmentary 'view of the calipering device shown in contact with the work piece,

Fig. 3 is a view on an enlarged scale of a portion of the apparatus shown in Fig. 1, being a vertical sectional view through the table and associated parts and showing the calipering apparatus in side elevation,

Fig. 4 is a plan view of the calipering device, certain hydraulic mechanisms being shown in section, and the scale being substantially that of Fig. 3,

Fig. 5 is a detail axial sectional view of the electrode calipering element and its mounting,

Fig. 6 is a view substantially on the scale of Fig. 4 of the calipering device, looking from the work piece toward the front of themachine,

Fig. '7 is a fragmentary front elevation of the front of the machine showing the calipering apparatus,

Fig. 8 is a side elevation of one calipering device showing different positions of the wiper,

Fig. 9 is a vertical sectional view taken on the line 9-9 of Fig. 3,

Another ob- Fig. 10 is in electrical diagram,

Fig. 11 is a hydraulic diagram showing the various parts in the position which they occupy when the machine is at rest, that is to say at the completion of a grinding operation and also prior to starting the machine in operation again,

Fig. 12 is ahydraulic diagram showing the parts in the position which they occupy after the gauges have contacted the work. piece and before the wheel has bee advanced to grinding position. Fig. 13 is a hy raulic diagram showing the parts in the position which'they occupy as the grinding operation starts, v

Fig. 14 is a similar diagram showing the condition after the first sizing gauge has operated, and prior to operation of the instrumentalities responsive to the second gauge, and

Fig. 15 is a view similar to Fig. a modification of the invention.

' Referring first to Fig. 1, the invention may be embodied in many different types of grinding machines, but so far as certain features thereof are concerned it is embodied in any type of grinding machine for the grinding of convex cylindrical surfaces. So far as certain features of the 5, illustrating invention are concerned it may be embodied in a center cylindrical grinding machine adapted to I grind by the so-called plunge-cut method; and the specific embodiment will be so described. By plunge-cut I mean grinding in which the wheel and the work piece move relatively to each other by-a substantially continuous motion without a wide relative traverse between the wheel and work, although a limited reciprocation or traverse may be employed in order to eliminate or reduce grinding lines. In such a machine, increments of transverse or cutting feed are usually not allocated to any particular phase of the reciprocating or traverse motion, if any.

Referring now to Fig. 1, I providea machine base of any desired structure on the front part of which may be ways 21 and 22 for the support of a work carriage 23." Adjustably fastened to the carriage 23 is a work table 241 having ways 25 and 26 for the support of a headstock 2V and a tailstock, not shown. The headstock 21 has, as shown in Fig. I, a center 28, and the tailstock has a center 29; the center 28 is mounted in a work driving spindle upon one end of which is a driving plate 30 having slots ii to receive the usual work driving dog. The spindle, not shown, may be driven by 'a belt and pulley or a motor or in any other desired manner. It will be appreciated that the foregoing represents the usual elements in a plain cylindrical grinding machine and any variations or changes may be made therein within the scope of this invention, and any other means for holding and rotating a work piece 32 may be employed, for example a,

work. gripping chuck might be used. The appa-' ratus shown is capable of supporting long work pieces and is capable of adjustment for different sizes of work pieces in so much as the headstock 21 and the tailstock, not shown, may be moved along the table 24 to any desired position and there securely clamped in place.

Still referring to Fig. 1, I'provide a grinding wheel 35. This wheel 35 may be mounted upon a spindle 36 which is journaled in bearings, not shown, in a wheel head 31; to the spindle 36 is attached a pulley 38 connected to a pulley 39 by means of one or more belts 46, the pulley 39 being driven by a motor 4I. Thus the grinding wheel 35 is driven at the desired peripheral velocity, and so far as this invention is concerned any type of wheel drive may be employed.

The wheel head 31 is mounted upon a feed slide 42 which is mounted upon ways, not shown, on the machine base 26, and which ways are formed to permit movement of the slide 42 perpendicular to the "axis of the work piece 32. Still referring to Fig. 1, on the under side of the slide 42 is a half nut 45 which engages a feed screw 46- to which rectilinear movement may begiven for advancing and retracting the grinding wheel automatically, and to which angular movement may be given for manually moving the grinding wheel and for compensating for wheel reduction due to normal Wear or dressing or truing thereof. More specifically, and according to this particular embodiment of the invention, I may provide a slide block 41 to which one endof nected by journals, not

shown, the slide block 41 being keyed by means I of a key and spline 46, 49 to .a guide member 56 provided in the machine frame, and the slide block 41 being connected by means of a piston rod 5| to a piston 52 in a fluid pressure cylinder 53 which is-closed by cylinder heads 54 and 55. Movement of the piston 52 in the cylinder 53 carries the grinding wheel 35 toward and away from the work piece 32.

Considering now the mechanism for manually moving the slide 42, and still referring to Fig. l, upstanding from a central horizontal frame member 26a is a journal 51 which journals a sleeve 58 to which is fastened a gear 59-. An extension 46a of the screw shaft 46 is splined by means of a key 66 to the sleeve 58. The gear 59 meshes with a ear 6| which is fastened to the end of a shaft 62 that is mounted in suitable bearings 63 and 64 in the machine frame. a gear 65 which meshes to a shaft 61 which is journaled in journals 68 and 69 in the machine frame. I provide a hand wheel I6 fastened to the shaft 61 for rotating the train of gearing described. Rotation of the hand wheel I6 procures' rotation of the feed screw 46; and it is noted that the thrust on the feed screw is taken by the fluid in the cylinder 53. Fluid pressure actuation of the piston 52 procures translation of the nut 45 by translation of the feed screw 46, and the portion 46a may move in the sleeve 58.

Considering now the control of the carriage 23, I may provide any mechanism for this purpose, such as mechanical power feed or hydraulic feed, but so far as certain features of the invention are concerned a manual adjusting apparatus may be used. Referring now to Figs. 1 and '7, I show a table positioning hand wheel 15 upon the shaft with a gear 66 fastened tively which together the feed screw 46 is -c0n- Fastened to the shaft '62 is meshes with a large gear 18 mounted on shaft I6 to which is fastened a pinion gear 86 meshing with a rack 8| fastened to the underside of the carriage 23. -'I'he:carriage 23 and therefore the table 24 may be moved to any position at any time by rotation of the hand wheel 15.

So far as certain aspects of the invention are concerned, the sizing mechanism maybe applied to or combined with many other types of grinding machines, but it is particularly applicable in connection with and in combination with a grinding machine having some of the elements and features of that above described. Considering now the sizing apparatus which is more specifically the subject matter of the present invention, and referring first to Fig. 3, I provide upper and lower angle calipering plates I66 and IN respecwith a central electrode calipering rod, I 62 constitute a Y-gauge or calipering-device for setting into action certain instrumentalities when the work piece reaches a desired size. Referring now to Fig. 4, so far as certain features of the invention are concerned and to achieve the control hereinafter specified, I provide similar sets of the Y-gauging instrumentalities, there being a second upper angle calipering plate MM, and as shown in Fig. 6 a second lower angle calipering plate I6Ia, and a second electrode calipering rod I62a. Figs. 4 and 6 show the relative position of these parts.

the lower angle calipering plates IM and I6Ia. are

respectively fastened to vertically slidable blocks I64.and I64a. Referring now to Figs. 3. 4, and 9, I provide vertical slidewaysl'65 and I65a on opposite sides of central gauging supporting members I66 and I66a respectively; these slideways are dovetailed slideways cooperating with dovetailed portions of the respective slides I63, I64, I63'a and I64a. The slideway I65 supports the slides I63 and I64 while the slideway I65a supports the slides I63a and I64a.

Referring now to Figs. 3 and 9., passing through nuts 6', III formed on the inside portions of the slides I63 and I64 respectively is a single adjusting screw shaft II2 having a knurled-head I I3.

- The upper portion of the screw shaft II2 has a separates the slides I63 and I64,

The screw shaft I I2 has a H5, and in the bearing H4 is a groove H6 in which fits the end of a stud I II for awurate location of the screw shaft II2.

Referring now to Fig. 4, there is a knurled head II3a of a screw shaft 2;: for similar adjustment of the slides I 63a and I64a, and the construction, mounting and arrangement of the parts for the left-hand gauging instrumentalities is the same as that already described for the right-hand gauging instrumentalities. Once a desired position of adjustment of the angle calipering plates has been achieved for either gauge, the parts may be locked in position, for example by means of wedge clamps I25, I26 (Fig. 7), I25a.

and I26a operated by screw members 121, I28, I2Ia, and |a respectively. I Considering now either set of anglecalipering plates, once they have been brought to adjusted position and clamped there they constitute a Y- gauge. As will behereinafter described, I prefer to provide instrumentalities for the adjustment of the gauge in a vertical direction so that the bisector of the angle subtended by the gauge plates will pass through the axis of the work piece. Rather than depend upon an absolute adjustment, however, I prefer to make the ultimate holding means for the gauges flexible to such an extent that each gauge will center itself upon the work piece. In order that wear of the angle calipering plates may be reduced to a minimum I prefer to embody them in separate detachabl pieces made of some hard material, for examp e hardened tool steel, Stellite, tungsten carbide, tantalum carbide, or boron carbide. I prefer the latter substance as it is extremely ha'rd'and can be formed to the desired shape.

As three points determine a circle. the respective electrode calipering rods I02 and I02a will contact the work piece at some definite diameter thereof, depending upon their positions of adjustment. Furthermore, the gauging instrumentalitiesdescribed are independent of expansion and contraction of supporting parts and independent of vibration or spring or other causes of maladjustment. A practical calipering device for a grinding machine ought to caliper .to a size of the order, of plus or minus .0002" or .0003. Therefore, the gauges of the invention which caliper by the geometric arrangement of instrumentalities rigidly clamped in position in a gauging head of small magnitude present marked advantages over certain previous types.

Considering now the adjustment of the electrode calipering rods' I02 and I02a, which will be described for the callpering rod I02; and referring more particularly to Fig. 5, the member I06 which as described constitutes the base for the support of the slides I03 and I04 which support the angle calipering plates, has a horizontal bore I30 of considerably larger diameter than that of the calipering rod I02, and inwhich bore I30 the calipering rod I 02 is located. The rod I02 is supported spaced from and insulated from the metal of the base I06 by means of an insulating bushing I3I at one end of the bore I30, the bore being slightly enlarged at that point, and by an insulating bushing I32 at the other end thereof, the bore I30 being also and substantially more enlarged at the other end. Be-

tween the insulating bushing I3I and the rod I 02 is a metal supporting sleeve I33 to reduce wearing of the parts, and in the bushing I32 is a nut I34 through which passes "a screw threaded portion I35 of the electrode I02. I provide a knurled insulating head I36 for the screw portion I35 and a check nut I31 with a knurled insulated head I38 in order to lock the rod I02 in' the contactor being hand screw I63, see Figs. 3 and '7.

cult through the terminal I 4| as will be hereinafter described.

The invention'contemplates certain instrumene talities and safeguards to avoid possible variations in accurate sizing due to arcing at the point ofv contact between the electrode rods I02 and I02a and also due to possible short circuiting through the coolant fluid, which is usually water. In the preferred'embodiment of the invention 'I avoid arcing by utilizing veryweak currents of low electromotive force, together with electronic amplifying. apparatus to'set into operation electrical instrumentalities of 'suflicient power to operate a heavy solenoid. With regard to the water, it may be mentioned that water not containing .a substantial amount of ions is not a good conductor of electricity. Consequently I propose to take advantage of the fact that a great increase of the current flowing through the electrodes I02 and I02a respectively will occur upon the contact thereof with the workpiece. But furthermore 'I prefer to keep the stream of water away from the electrodes as much as possible, and to this end I have provided the wiping and sealing apparatus now to be described.

As shown in Fig, 2, I provide a rubber sleeve I 44 fitting the electrode I 02 and secured thereto by a ring I45, which sleeve, in contact with the .work piece 32, operates'as a cup to exclude water from the area enclosed by it. I further provide a slot I46 to drain away any moisture which gets past the cup M4. The electrode rod I02c has a similar member I44a attached to it, see Fig.6.

Referring now to Figs. 8 and 9, mountedon the gauge supporting. member I06a is a bracket I48 supporting a pin I4'I upon which is pivotally mounted a. lever I49. At that end of the lever I49 which is nearest to the work piece 32 is mounted a splash plate I50 on the bottom of which is a wiper member I5I, preferably made of rubber or other flexible material. On the end of the lever I49 opposite the splashplate I50 I provide a projection I 52 which is positioned to contact, ,an inclined member I53 mounted on a cylinder head I54. When, as will be hereinafter described, the gauging member i06a moves forwardly relative to the cylinder head I54, the lever I49 is rocked by engagement .of the projection I52. with the inclined member I53, and this not only moves the wiper I5I forwardly, but also swings it downwardly to engage the work piece 32. The plate I50 and wiper I5I are of suflicient width in the direction of the work piece axis to shield both rod terminals I02 and "Ma.

Referring now to Figs. 3, 4, and '7, mounted upon the machine base 20 is a bracket I55 which has horizontal guideways I56. I provide a slide I5I mounted in the guideways I56, which slide I5I has an upwardly and rearwardly extending support I5Ia. Secured to the under side of the slide I51, as better shown in Fig. 3, is a nut I56.

On the front of bracket I55 I provide a split journal I59,v I60, supportingan adjusting screw I6I the screw threaded part of which is engaged by the nut I50, and axial motion of the screw shaft I6I relative to the bracket I55 is-prevented by collars I62 and I62a. By turning the square end of' the shaft I6i, as with a wrench or the like, the slide I57 may be adjusted forwardly or rearwardly of the machine, and when the desired position of adjustment is achieved the parts may be securely clamped in position by means of a Referring to Figs. 3 and 4, secured to the upper end of the upwardly extending portion I5'Ia is a cylinder I60 either end thereof.

Considering now the fluid pressure actuation of the cross slide 42, as well as other fluid pressure apparatus, and referring more particularly to Figs. 1 and 11, integrally formed with the base 28 is a fluid reservoir I 68 for the collection and supply of oil or other fluid used in the fluid pressure operating apparatus. I provide a pump I89 which may be of any suitable type and driven from any source of power, not shown. A main pressure line I18 receives fluid from the pump I69, and shunted into the line I18 is a pressure relief valve I1I of any usual or desired type. I provide a valve casing I12 having an internal cylindrical bore, the ends of which are blocked by valve heads I13 and I14, the head I14 being in the form of a cover plate and the valve casing I12 being supported by it. I provide a valve rod I15 having spaced piston portions I15a, I'I5b, I150,

- and I15d.1 The valve rod I15 extends through the cylinder heads I13 and I14 and is connected to a hand operating lever I16, as shown in Fig. 1. That partof the valve rod I15 which is outside of the valve head I13 has a plurality .of notches I11,

I18, and I19 for engagement by a detent I88 which is pressed into engagement with one of the notches by a spring I8I in a detent casing I82. Connected to the valve rod I15 at its rear end is a lever I83 pivotally mounted on a pin I84 supported by a bracket I85 projecting upwardly from the machine base 28, and this lever is automatically operated during a cycle of machine operation, as will be hereinafter described.

Still referring to Figs. 1 and 11, on the rear of the machine I provide another valve casing I86 having heaQsJN and.|88. In the casing I86, the bore of which is cylindrical, is a piston I89 having annular grooves I98 and I9I. The piston "I89 is urged upwardly by means of a spring I92 located between the bottom of the piston I89 and i the head I88.

With the machine parts in the position shown in Fig. 1, that is to say with the grinding wheel 35 retracted from the work piece and with the calipering plates I88 and I880, and associated parts also withdrawn, the various instrumentalities of the fluid pressure actuating apparatus are in the respective positions thereof shown in Fig. 11. Fig. 1 also illustrates to a certain extent the positions of the various parts between grinding operations. Referring, therefore, particularly to Fig. 11, and also to Fig. 1, and describing a condition of static pressure. as a flow of the pressur'e'fluid through.

the channels through which it flows while it is actuating the parts, the pressure .fluid flows from the pump I69 along piping I18 and 288 to an entrance port 28I in the cylinder I12 and thence by an exit port 282 along piping 283 to, the front end of cylinder 53, thus holding the wheel slide retracted. There is a shunt pipe 284 connectedto the pipe 283 which leads the fluid to the rear end of the cylinder I64 in which is located a piston 285 connected by means of a piston rod 286 to a cross head 281'in which are slidably supported the central gauging supporting member I86 and I86a, all as more clearly shown in Fig. 4. Thus with the piston 285 inthe position shown in Fig. 11, the cross head 281 is forwardly ofthe machine, that is retracted with respect to the work piece, and both gauges are withdrawnn Connected to the cross head 281 are forwardly extending portions..2l8 and 2| I, the portion 2I8 supporting a cylinder block 2I2 having formed shown in Fig. 11.

to a cross piece 228a which is rigidly attached to the central gauging supporting member I86. In the cylinder 2| 6 is'a piston 22I connected by means of a piston rod 222 to the central gauging supporting member I86a. Referring to Fig. 11, pressure fluid may at all times flow from the main supply line I18 into a pipe 223 and through .a restricted orifice valve 224 to piping 225 leading to the front end of each ofthe cylinders 2 and 2I6. Thus at all times the central gauging supporting members I86 and I86a are urged rearwardly of thernachine, that is toward the work piece, butwith the piston 285 in the position The gauges are nevertheless not in contact with the work. The fluid pressure means embodied in the cylinders 2I4 and 2 I6 and pistons 2I8 and 22I are provided in order to effect a pressure contact of the gauges against the work piece and to allow the gauging instrumentalities to follow up the work as it is reduced in diameter. Furthermore, by means of the cylinder 2I3 and piston 2I1 I am enabled to withdraw the righthand gauging instrumentalities prior to withdrawal of the left-hand gauging instrumentalities, by fluid pressure actuation, in so much as of the pistoii 2I8. But with the parts in the con dition shown in Fig. 11, the front end of cylinder 2I3 is opened to the exhaust as follows:

Piping 238 connects the front end of the cylinder 2I3 to piping 23I which leads to a port 232 which, with the wheel and gauges retracted, registers with groove I9I which, therefore, connects port 232 to a port 233 towhich is connected piping 234 which connects to piping 235 which leads to the reservoir I68.

Assuming that the operator has placed an unground work piece 32 between the centers 28 and 29 and caused the driving spindle and driving plate 38 to revolve, when he wishes to cause the grinding operation to commence he draws the lever I16 forwardly to the position where the detent I88 engages the notch I18, and this causes both sets of gauging instrumentalities to advance into contact with the work piece as follows:

Referring now to Fig. 12, the port 282 is now disconnected from the port 28I but the piping 248 which connects to the rear end of the cylin-- der 53 is not connected to the pressure-side so there is no tendency for the wheel slide to move forward. Instead, both sides of the cylinder 53 are connectedto the reservoir I68, the front side by way of piping 283, port 282, port 24I and piping 235, and the rear side by way of piping 248, check valve 242, piping, 243, piping 244, port 245, port 246 and piping 241 to piping 235. The port 28I is, however, connected to port 258 which is connected by way of piping 25I through a restricted orifice valve 252 to the front end of the cylinder I64, which forces the piston 285 rearwardly. At the same time, pressure is admitted through piping 223, restricted orlflce valve 224, and piping 225 to the front ends of the cylinders 2I4 and 2I6 so that, as the cross head 281 and, therefore, the portions 2I8 and. 2H and the cylinder blocks 2I2 and 2I5 are moved toward the work pieces, the central gauging supporting members I86 and I86a are likewise carried forward, but as soon as the respective gauges con- 'the diameter of the piston 2 I 1 is greater than that tact the workpiece they and their supporting members I66 and I661; may stop while the rest of. the parts move forwardly responsive to movement of the piston 265. I

It is desirable that the operator be able to move the gauges into position without moving the grinding wheel, in order to set up the machine, including the adjustment of the gauges and for other purposes, and in the machine of the invention the gauges may be moved back and forth prior to the commencement of grinding anynumber of times, by moving the hand lever I16 between its full line position, Fig. 1, and the intermediate dotted line position there shown. Whenever 'the, operator wishes to cause the grinding operation to'commence, whether the gauges have been previously advanced or not, he

moves the lever I16 to the left-hand dotted line position, Fig. 1, thus moving the notch I16 under the detent I66, and this brings the grinding ,wheel 35 against the work piece 32 to'start the grinding operation, the pressure fluid apparatus having moved and being then and thereafter until further actuation in the condition shown in Fig.' 13, as follows:v

Fluid is still admitted to piping 25I and fluid is still admitted to piping 225, thus the condition of. the gauging instrumentalities remains the same. But fluid is now admitted to the port 245 and, by way of 'piping 244, to a port 266. Opposite to the port 266 is a port 26I connecting by way of piping 262 to the piping 246 which, as will be remembered, connects to the far end of the cylinder v53. Immediately the operator has moved the lever I16 to the most forward position,

the piston I89 is in the position shown in Fig. 12,

' and the groove I96 connects the ports 268 and 26I to allow the fluid to flow, and furthermore, to allow an unrestricted flow. Referring now to Figs. 1 and 13, the piston rod I extends rearwardly of the machine and has located thereon a cam 263 and a trip block 264', and the cam 263 is preferably adjustable upon the piston ,rod 5|. In the path of ,the cam 263 is a knob 265 on the end of a screw 266 which is adjustably' mounted on the upper end of the piston I68; downward movement of the knob 265 moves the piston I66 to the} position shown in Fig. 13, or other desired adjusted position, to restrict the flowof fluid from port ,266 to port 26I and therefore cause'a, slow or feeding movement of the cross slide to effect the desired grinding operation. The cam 263 will ordinarily adjusted so that the cross slide is slowed down just prior to actual contact between the grinding wheel and the work piece. By the provision of thismechanism I am enabled to avoid loss of time in bringing the grinding wheel into contact with the workpiece, and at the same time I procure the desired slow movement of othe cross slide for the preliminary {feeding operation tol reduce the work piece in diameter. W Considering now more particularly the construction of the valve I66, it includes apoppet valve portion 216 and the valvecasing I66 has a seat 2" for the portion 216 so that, when the valve I69 is moved to its lowermost position the ports 266 and 2 6I are separated by afluid pressure" seal which permits no fluid to pass through; with the parts in the position-of Fig. 13, however, fluid can flow slowly through a narrow slot .212 in a cylindrical portion of the member I69 just below the poppet' valve portion 216.-

The grinding operation proceeds by the slow entrance of fluid into the rear end of the cylinder 53 causing the grinding wheel to approach the work piece until such time as the work piece is reduced sufficiently in diameter to cause the right-hand gauge electrode I62 to contact the work piece 32; whereupon a very minute current flows through the electrode I62 which, beingduly amplified, causes energization by a strong current. of a solenoid 215 which draws downwork piece. This action can take placeby rea-' son of the differential in sizes of the pistons 211.

and 2I6. The pressure fluid reaches the rear of the cylinder bore 2I3 by way of piping I16, piping 266, port 26I, port 245, piping 244,, shunt piping 218, port 219 groove I9I, pc 266, shunt piping 281 and the piping 236. It wil be noted from inspection of Fig. 14 that the valve I15 is in the same position it was while the grinding wheel was moving toward the work-piece.

'The'grindlng wheel is now prevented from further approaching the work piece, but grinding continues by reason of the pressure set up inthe machine and such grinding is usually termed sparking out. The second gauge point I62a is set so that when the work piece is brought to the desired finished size, it will contact therev with. During the finish grinding, while the flnal and. finishing cuts are being taken on the work piece, this being a gradually dying-out grinding operation, the right-hand gauging instrumentalities including the electrode I62 are removed from the work piece. This avoids undue wear of the gauging apparatus. When the electrode 162a contacts with the work piece, a very weak current flows therethrough which is amplified and a current backed by a. strong electromotive force energizes a. solenoid 282 which has a core 283 which is'connected by means of a link 284 to the lever I63. Movement of the solenoid core 263 swings the lever I63 to the position shown in Fig; 1, thus moving the valve *I15'back to its original position, causing the piston 265 to move' forwardly and retracting the entire gauging head, which has the effect of moving. the second gauge away from the work piece; at the same time fluid is admitted to the front of the piston 52, retracting the grinding wheel from 'the work piece.

Considering still furtherthe fluid pressure apparatus, the check valve 242 is provided 'so that,

during the normal grinding operation, prior to contact of eithergauge electrode, the ,fluid will be forced to go through the restricted-passage 2611 rather than by way of piping 246; on the other hand, when the-wheel slide is -moved away.

from the work piece, it is desired that the movement be a'rapid one, unimpeded by any resistance at the start thereof, and ac cordingly check v lv 242 and piping 246 is a shunt between the rear side of the cylinder 53 and the piping 244 and thus, to the port 245 which, when the valve I15 .is. in its initial position, is connected to the reservoir I66. The valve 252 is an adjustable valve and therefore, if desired, the approach of the gauges toward the work piece may be at a. 1 very slow rate, and at the same time the operator may move the lever I16 from the upright posi- 5 tion to the extreme forward position with a single motion; under such circumstances the grinding 'wheel 85 will contact the work piece before the gauges contact it, and it is desired to be. able to control the machine this way for grinding rough work pieces that have not been previously ground or have not even been previously machined, in order to avoid undue wear of the gauging instrumentalities by work pieces having an excessive amount of scale or other foreign hard matter thereon, or which are unduly rough or irregular.

Considering now the manner and means by which contact of the electrode I02 or the electrode l02a sets in operation the various instrumentalities described by energizing respectively the solenoids 215 and 282, and referring more particularly to the diagrammatic view of Fig. 10, with reference to Fig. 1 for certain mechanical instrumentalities, the right-hand end of piston is a switch box 296 adjustablye supported by means of a bracket 29'! attached to the valve casing I86. In the switch box 296 is a switch lever 298 mounted on a trunnion pin 29 9 and having on its upper and left-hand end a roller 800. A spring 80l urges the lever 298 in a clockwise direction, while a block 802 acts as a stop to inhibit movement beyond the limit shown in Figs. '1 and .10. The right-hand end of lever 298.carries an insulated contact strip 808 adapted to contact a strip 804. Except when the roller 800 is depressed by the trip block 294, the circuit is open between contact strips 808 and 804,

but whenever the trip block 294 rides over the roller, the circuit is closed.

I provide any suitable sourceof alternating current, for example 110 volts, cycles, represented on Fig. 1-0 by the main power lines 805, 806. Connected across these lines 805 and 806 is a transformer primary 801, by means of conductors 808 and -809. Similarly, a transformer primary 801a is connected by conductors 808a and 809a to/ the power lines 805 and 80.6.

- Transformer secondaries 810 and 810a are connected by conductors 8H, 8l2, and 8lla and 8|2a respectively to filaments H8 and 8l8a respectively of triode tubes 8 and 8l4a. The mid point of the secondaries M0 and 8| 0a are rounded as shown. r

The grids M6 and 8|6a of the tubes are connected by conductors 811 "and 811a to condensers 8I8 and 8|8a and also non-inductive rheostats 8N and 8|9a in parallel. These instrumentali ties are connected by conductors 820 and 820a to 60 inductances 82l and 82la which are connected I by conductors 822 and 8220 to the electrodes I02 and 12a by way ofthe terminals I .and la, as alreadydescribed. Each work piece 82 is, of course, grounded by reason of the fact that it is 1 mounted between the centers 28 and 2,8. It will now bef'seen that when an electrode, for example the electrode I02, touches the work piece 82, the grid 816 isgrounded through the rheostat 8l9 and inductance 82l, and in so much as the mid point of the transformer M0 is grounded, the

triode tube oscillates. In the tube 8 is a plate 825, and in the tube 814a is a plate 825a. These plates are respectively connected by conductors 826 and 826d to inductances and'variable condensers in parallelrespectively' 821, 821a, 828,

rod 5lhas thereon a trip block 294 and below it and 828a which are connected by conductors 888 and-880a to radiofrequency choke coils 88l .and 881a and thence by way of conductors 882 and 882a to sensitive relay coils 888 and 8884. The otherside of the relay coils is connected by conductors 884 and 884a to the line805. Main power line 806 is grounded, as shown, at885. The reason for the inductance 821 and variable condenser 828 is to tune the'plate circuit into resonance with the grid circuit, thereby permitting the tube to oscillate. The amount, of current flowing through the electrode I02 can be adjusted by the rheostat M9. The foregoing characteristics are also true of the inductance 821a, variablecondenser828a and the rheostat 8| 9a, respectively. For each circuitI-provide a grounded by-pass condenser 886 and 886a, respectively. v a

The sensitiverelays 888 and 888a respectively have relay swit es 881 and 881a, one side connected by cond ctors 888 and 888a to the power iine 805 and the other side connected by conductors 889 and 889a to relays 840 and 840a. Conductors 8 and 84|a connect the other side of these relay coils to the power line 806. Thus when either one of the sensitive relays is energized, a power circuit through the relay controlled by it is closed, and this closes one or the other of knife switches 848 and 848a. The knife switch 848 controls operation of solenoid ,215, while the knife switch 848a controls operation of the solenoid 282. One end of each. of these knife switches is connected by conductors 844 and 8440 respectively to the power line 806, and the other ends of the knife switches 848 and 848a are connected by conductors 845 and 845a respectively' to thesolenoids 215 and 282, the other sides of the solenoid coils being connected by means of conductors 846 and 846a respectively to the line 805.

Thus when the grinding operation has proceeded far enough to cause the electrode I 02 to contact the work piece 82, the tube 8|4 draws current which energizes the sensitive relay 888' which causes. energization of the relay 840which closes a knife switch energizing the solenoid 215. Furthermore, when the work piece is finished and the electrode I020 contacts the work piece,.the tube 8l4adraws current which energizes the sensitive relay 888a, this causing energization of the.relay 840a which closes the knife switch 848a and operates. the solenoid 282.

When the grinding wheel is approaching the work piece, but not actually in contact with it, and-also when the grinding wheel is receding from the work. piece, the trip block 294 strikes the roller 800 and this closes the circuit between the contact strips 808 and 804 momentarily. The strip 808 is connected by a conductor 850 to the power line 806, while the strip 804 is connected by a conductor 85l to a pair of conductors 852 and 852a leading to solenbids 858 and 868a,

the other ends of the coils of which are connected by conductors 854 and 854a to the power lines 805. These solenoids 858 and 8581: are connected to the knife switches 848 and 848a so. that when the solenoidsare energized the switches'wiil'be opened. Thus all switches are opened atthe start and before the start of a grinding operation. By reason of the provision of the knife switch 848, the solenoid 215 remains energized even after the electrode I02 has been a removed from the work piece by the fluid pressure withdrawal thereof which waspreviously describedi Furthermore, even momentary closarcane ing of the sensitive relay control contact 331a causes closing of the'knife switch 343a and so the solenoid 282 is operated, if mail, We. steady and powerful current. The same is true of the solenoidv 215. But whenever the grinding wheel runsaway from the work piece by retraction of the cross feed slide, which isbound to happen when the solenoid 282 is energized, both knife switches are opened by the automatic means herein described.

A particular feature of the invention resides in the fact that the metallic contact electrodes are in contact with the work piece, during each particular grinding operation, for an instant only, and consequently wear thereof is mini- .mized. Another feature of the invention resides in the fact that the gauging apparatus is not dependent upon the relation of some machine part connected through the machine base and carriages and tables to the work piece, but a true gauging operation upon the work piece itself is. effected. Nevertheless the only elements which continuously contact the work piece, viz. the plates I80, IOI, lilila, lflla, do not transmit electricity and may be made of any hard and wear resistant substance as already stated. By reason of the provision of electronic amplifying. apparatus a current so small that it will not arc is all that is. carried by the electrodes, and nevertheless this is amplified and operates relays to operate the machine, controlling solenoids with a full strength and dependable current. By

\ reason of the provision of the rheostats 3l9 and against the work piece.

sensitive relays. 333, the apparatus can be adjust- 1 ed so that it will not be operated by whatever current leaks through the grinding water but only-when actual metal contact is made.

Another feature of the invention resides in the fact that there are no moving parts in the callpering head which move during the calipering. operation. The calipering head as a whole'is urged towards the work piece and, while it is gauging, each Y-gauge'mechanism is maintained While both the head as a whole and each gauge separately are individually movable, nevertheless the relative position of the Y-gauge parts remains fixed during a given machine operation. Furthermore, means for rigidly attaching and securely anchoring the several parts of each gauge mechanism has been shown and described. The result is that variations in gauging due to stresses within the gauging parts are practicallyeliminated.

Another feature of the invention resides in the means for ready adjustment of the calipering head toward and from the machine centers and 29. This is a feature of practical importance in so much as itpermits the calipering device to be set up for many difierent sizes of work pieces. This feature is, as already described, independent of the automatic advance and withdrawal of the calipering'head by fluid pressure means.

Along with the feature just mentioned is the adjustability of each Y-gauge. This permits each gauge to be individually adjusted for the sizing of different work pieces. Nevertheless, by means of the wedge clamps, the-parts of each gauge can be so firmly secured in position as to eliminate variation in the ultimate sizeof a work piece by slipping of the parts at the adjustable Still another feature of the invention resides in the fact that the central plane of the electrodes I02 and IBM does not have to be in the horizontal plane of the centers 28 and 29 to an accuracy of more than .002" 01 .003". It is theoretically possible but practically very dimcult to .builda machine tool with separate parts so closely aligned and without the possibility of misalignment. But the bracket l51a is more or less resilient owing to its length and consequently the gauges are self-adjusting upon the work piece within the limitations of a few thousandths of an inch and by reason of the pressure exerted upon them. The bracket IB'la is preferablymade of steel or malleable iron so as to allow it to be slightly bent to bring the central plane of the gauging headsto that position where they will most readily adjust themselves upon the work pieces. 1

Anotherv feature of the invention lies in the fact that it is possible to bring the .wheel into contact with the work piece before the gauges and, on the other hand, it is possible to bring the gauges into contact with the work piece before the. wheel. F 'iirthermoraby shifting the lever i16,'the gauges can be moved against and away from the work piece as many times as desired without causing engagement of the work scratch the work piece. These plates I00 and I0! and the corresponding plates .illila and "Na act as steady rests since they are urged against the work piece by fluid under pressure. Thus the apparatus is not only a gauging apparatus but also acts as a steadyrest.

The automatic advance or withdrawal of the gauges separately and together is a feature contributing to make the machine automatic and, furthermore, wear upon the electrodes is reduced to an absolute minimum by reason of thefact that the barest contact of each with the work piece is all that takes place during the grinding and gauging of that work-piece.

.Still another feature -of the invention resides in the organization of the gauging apparatus whereby the operator is allowed full and free access to the work piece to inspect the same and, moreover, the operator is not interfered with in the loading of the machine. In the embodiment of the invention described there are practically no overhead parts.

It has already .been mentioned that the gaug- -ing. apparatus also acts as a steadyrest. Itsaction as a steadyrest is enhanced by reason of the fact that it is always located opposite the wheel. Furthermore, this permits the use 'of the apparatus describedin connection with a grinding operation in" which a relative traverse between wheel and work piece is employed. If the work piece is a uni-diameter shaft, relative reciprocation between the work piece and the gauges is entirely practical in accordance with the disclosure of the present invention 7 Referring now to Fig. 15,'I have therein disclosed a modification of the invention according to which some of the features of advantage already mentioned though not all thereof are achieved. The modified apparatus may be'employed especially in cases where dry grinding is practiced the gauging apparatus already described. Re

ferring now to Fig. 15, I provide an adjustable of the terminals I or Illa. In place of the' electrodes I02 and I02a'I provide a contact rod I021: having a tip of hard and insulated material IIJZy, which material may be boron carbide. This rod I021: is mounted between a collar i330:

and the front of the main supporting sleevellliw.

A spring 360 acting against a collar 3 and reacting against the collar I332: urges the rod I023: toward the work piece. The tip "121:, therefore, continuously-contacts the work piece, and when the work piece comes to the desired size, whether for cessation of cross feed advance or for wheel withdrawal or for other purposes, the rod I022: strikes the end of the plug 135x, and accordingly the current through terminal wire mm is grounded. In this case the actual contact is made in a closed box amply insulated.

-The disclosure herein is identical with that in the copending application'serial No. 60,479 filed January 23, 1936 of George Crompton, Jr. and Clarence J. Green, but the subject matter of the following claims is my own separate invention.

It will thus be seen that there has been provided by this invention an apparatus in which the various objects hereinabove set forth together with many 'thoroughly practical advantages are successfully achieved. As many-possible embodiments may be made of the above inventionand as many changes might be made in the embodiment above set forth, itis to be understood thatall matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claimzv 1. In a grinding machine, a grinding wheel, means supporting a work piece in position to be operated upon by the grinding wheel, a pair of gauges, a support for both of said gauges, means urging said support towards the work piece, a second support for one gauge mounted upon said first support whereby the gauges may. measure the work piece to diflerent sizes, and means for. withdrawing the first named support.

2,.In a grinding machine, a grinding wheel, means supporting a work piece in position to be operated upon by the grinding wheel, a pair of gauges, a support for both gauges, fluid pressure means to move said support towards and from a work piece, a second support mounted on sad first support and-directly connected to one of the I gauges, and fluid pressure means for the second support upon the first support to urge the gauge held thereby towards. the work piece allowing differential movement of the gauges.

3. In a grinding machine, a grinding wheel, means supporting a-work piece in position to be the gauges towards the work piece the, gauges operated upon by the grinding wheel, a. pair of gauges, a mounting for said gauges to move them both towards and from a work piece, a further mounting for one gauge upon the first mounting permitting differential positioning of said gauges, and fiuid pressure means for-moving the first mounting.

4. In a grinding'machine, a grinding wheel, means supporting a work piece in position to be operated upon by the grinding wheel, a pair of gauges, a main, support for said gauges, fluid pressure means to actuate said main support to carry thegauges toward and away from the means supporting the work piece, a pair of additional supports, one for each gauge, mounted upon the main support, a pair of individual fluid pressure operated devices, one for eachot said last named supports, urging said supports in the direction of the means to support a work piece, and further means for withdrawing one of said last named supports prior to the other thereof. I

5. In a grinding machine, a grinding wheel, means supporting a work piece in position to be operated upon by the grinding wheel, a pair of gauges, aslide for said gauges, m ans urging 1th respect to said slide, means to move the slide to carry both of the gauges into and out of. operative relation to the workpiece, and additional automatically operated means to move one of the gauges on the slide away from the work piece.

6. In a grinding machine, a grindingwheel,.

means supporting a wcrk piece in position to be operated upon by the grinding wheel, a pair of gauges, a slide for said gauges, means urging the gauges towards the work piece with respect to said slide, means to move the slide to carry both of the gauges into and out of operative relation to the work piece, and additional automatically operated. fluid pressure means to move one or on the slide away from the work piece.

'7. In a grinding machine, a grinding wheel,

means supporting a work piece in position to be operated upon by the grinding wheel, a. pair of gauges, 'a slide for said gauges, means urging the gauges towards the work piece with respect to said slide,-'fluid pressure means to move the slide-to carry both of the gauges, into and out of operative relation to the work piece, and additional automatically operated means to move one of the gauges on the slide away from the work piece.

8. In a grinding machine, a grinding wheel, means supporting a work piece in position to be operated upon by the grinding wheel, a pair of gauges, a slide for said gauges; fluid pressure means urging the gauges towards the work piece with respect to said slide, means to move'the slide to carry both of the gauges into and out of operative relation to the work piece, and additional automatically operated means to move one of the gauges on the slide away from the work piece.

FRANKLIN E. JOHNSON. 

